From underground tunnels to private hair salons, Mansion’s list of the most outlandish, alluring and downright distinctive home features chronicled this year

They call it the amenities arms’ race: The drive among real-estate developers (and, increasingly, private homeowners) to equip their properties with ever more opulent and unpredictable features. For developers, the goal is to woo a wealthy clientele. For homeowners, it is to maximize enjoyment—and resale value.

Here, a roundup of some of the more memorable amenities to appear in the pages of Mansion this year, plus seven unique homes we covered in 2015.

GARAGE TURNTABLES

SANDY HUFFAKER FOR THE WALL STREET JOURNAL

Car turntables, a fixture of car shows and dealer showrooms, are the shiny new toys of prestige real estate. Developers of luxury properties are installing electronic car turners both for the wow factor and for their practical advantages in tightly designed lots with narrow driveways or limited turnaround space. Read more: Garage Turntables Take Your Car for a Spin

It’s brazenly impractical, and as one owner found out, perhaps not the best feature for resale value. Still, builders and architects say a handful of determined luxury homeowners have successfully installed slides in their own abodes. Read more: Squeezing a Slide into the House

MAN CAVES

LORI EANES FOR THE WALL STREET JOURNAL

Now, more men are investing in the spaces that used to be rarely seen by guests: the hobby room, the potting shed, the reading nook, the TV room. Read more: Man Caves That Aren’t for Cave Men

Prized for their cathedral-like architecture and antique wood patina, centuries-old post-and-beam barns are being reborn as full-blown entertainment facilities, complete with bars, caterer-friendly kitchens, and guest bedrooms. The rustic look comes at a premium, with prices for vintage party barns starting in the hundreds of thousands of dollars. Read more: After a Million-Dollar Makeover, Behold the Party Barn

WINE-TASTING ROOMS

MEGGAN HALLER/KEYHOLE PHOTO FOR THE WALL STREET JOURNAL

Oenophiles are increasingly pairing their wine cellars with sizable tasting rooms. These spaces are designed for entertaining and outfitted with practical features, such as dishwashers for stemware and warming ovens for hors d’oeuvres. Here, guests have space to spread out and can sip and nosh in shirt sleeves if they’d like. Read more: Wine-Tasting Rooms Move Out of the Cellar

PRINCESS-THEME BEDROOMS

LISA CORSON FOR THE WALL STREET JOURNAL

Princesses have long enchanted little girls. But cultural flash points in recent years, such as Disney’s blockbuster “Frozen” and Prince William’s royal wedding, have fueled demand for increasingly elaborate—and expensive—fantasy rooms. Read more: Princess Bedrooms That Rule

TUNNELS

CHAD HOLDER FOR THE WALL STREET JOURNAL

Magical and mysterious, tunnels in private homes have long bewitched homeowners with the bank accounts to build them. Now, tunnels have emerged as a unique amenity with handsome décor, as high-end builders seek to set themselves apart at a time when every house seems to have a wine cellar and media room. Read more: Luxury Homes Tout Underground Tunnels

HIDDEN POOLS

It is straight out of James Bond: Push a button, and the backyard patio begins to sink. Water rushes in. In less than 10 minutes, you’re staring at your secret swimming spot. Designed for commercial settings, the system behind the hidden pool, known as a movable floor, is now being adapted for residential use by a handful of manufacturers. Read more: The Super Cool ‘Disappearing’ Pool

HOME SPAS

DOROTHY HONG FOR THE WALL STREET JOURNAL

As more people consider spa treatments essential to health and well-being—as well as a fun way to entertain guests—wealthy homeowners are willing to pay a large premium to access the whole menu at home. Private, in-home spas with specialized features like massage rooms, pedicure chairs and hammams, or Turkish baths, are becoming more common, spacious and luxurious. Read more: Home Spas That Rival Those in Big Hotels

An IndyCar Racer’s Palace

Nazareth, Pa.

FOR THE WALL STREET JOURNAL

Five years ago, at age 23, accomplished IndyCar racer Marco Andretti bought a Pennsylvania house—along with its six-hole golf courses, cascading koi ponds, interlocking pools, 500-bottle wine cellar, six-car garage and 10 rolling acres—from his father, Michael, for $2 million. There is also a two-story domed rotunda with a Greco-Roman fountain as a centerpiece and a sky bridge leading to a glass-walled gym. Read more: IndyCar Racer Marco Andretti’s Pennsylvania Palace

A Restaurateur’s Retreat (With Teepee)

Bucks County, Pa.

DOROTHY HONG FOR THE WALL STREET JOURNAL

After visiting a friend in Bucks County, Pa., Manhattan restaurateur and real-estate adviser Mark Amadei realized he had found his ideal: a bucolic, wooded countryside with meandering brooks. Outside, he set up a Sioux-style teepee for yoga sessions and added a variety of rugs, kilims and pillows, along with a Maison Jansen campaign bed. Read more: Mark Amadei’s Country Mile of Luxury

A Real Estate Developer’s Portfolio

Greenwich, Conn.

FOR THE WALL STREET JOURNAL

The one thing that all real-estate billionaire Charles Cohen’s homes have in common is that they’re all meticulously planned and executed. At his house in Greenwich, Conn., there is a throwback 24-seat movie palace in the basement, with a ticket booth and vintage movie posters, modeled after the 1920s Paramount Theater. Read more: Charles S. Cohen’s Perfectionist Real-Estate Portfolio

Le Palais Royal

Hillsboro Beach, Fla.

Modeled after the Palace of Versailles in France, Le Palais Royal in Hillsboro Beach, Fla., has more than $3 million worth of gold leaf, six waterfalls, a master suite with a heated plunge pool on the balcony, an 18-seat IMAX home theater, a 30-car subterranean garage and a 1,300-gallon built-in aquarium. Read more: Florida’s Le Palais Royal Boosts Its Price Tag to $159 Million

A Party Penthouse

Las Vegas

LISA CORSON FOR THE WALL STREET JOURNAL

Benson Riseman’s penthouse apartment on the Strip in Las Vegas has a James Bond-like aura. A one-way mirror behind the bar allows Mr. Riseman to see people in the living room. What looks like an ordinary (albeit leather-covered) wall behind the dining area disappears at the push of a button, revealing a secret room. A coffee table rises and turns into a conference table, and a Murphy bed hides behind a purple sofa. Read more: A Penthouse Playhouse in Vegas

The Park Bel Air

Los Angeles

In a new development of three spec homes in the tony Los Angeles neighborhood of Bel Air, one property will have a 15,000-square-foot guesthouse. Another home has plans that call for a “Champagne room,” a chilled, glass rotunda with walls filled with bubbling liquid. A third home will have a 2,100-square-foot spa with separate steam and massage rooms. Read more: Where Prices Start at $115 Million: Bel Air’s Trophy Home Boom

A Home (Train) Depot

Standfordville, N.Y.

JULIE BIDWELL FOR THE WALL STREET JOURNAL

“The Station,“ a converted train depot in the Hudson River Valley, measures roughly 3,000 square feet. The front door opens to the high-ceilinged living room—originally the waiting room of a train station on the Poughkeepsie and Connecticut Railroad. The centerpiece of the room is the original ticket booth, which now serves as a landing for a spiral staircase that leads up to the master bedroom (once a storage attic). Read more: A Train Station Transformed